1. Field of the Disclosure
The present disclosure relates to a large-capacity sheet storage device that stores sheets and that feeds sheets to an image forming apparatus such as a copying machine, a printer or a facsimile. More particularly, the present disclosure relates to a method of enhancing the performance of setting sheets in sheet stacking means.
2. Description of Related Art
For example, when a large number of users share one image forming apparatus, the number of sheets that are used per image forming apparatus is increased. Hence, a large-capacity sheet storage device that further increases the number of sheets which can be stored therein is being developed.
For example, there is known a large-capacity paper feed device in which a tray that stacks sheets within a tray unit is supported by an elastic support member (coil spring) and thus the tray is prevented from rapidly dropping when the tray is separated from a drive portion. Moreover, there is known a sheet feed device in which, when the door of a sheet storage unit is opened, a force that acts to raise sheet stacking means is released and thus the sheet stacking means is rapidly lowered to the bottom of the sheet storage unit without use of power of a motor or the like.
Furthermore, there is known a copying machine incorporating a large-capacity sheet tray in which a brake dumper having a cam and a brake plate provided at one end of a wire winding shaft is included, thus the downward speed of a sheet stage is maintained regardless of the remaining number of sheets, a sheet stage downward movement waiting time is reduced and safety is enhanced.
Since, in the large-capacity sheet storage device as described above, a thousand or more sheets are supplied, when the sheets are supplied, a user supplies those sheets into a sheet storage cassette (sheet storage portion) by performing a plurality of rounds of sheet supply.
However, since, in the configuration described above, the sheet stacking means such as the tray and the sheet stage is lowered either to the lowermost part of the sheet storage portion or to the vicinity of the lowermost part, when sheets are set, the side wall of the sheet storage portion may become an obstacle. Consequently, there is possibility that the workability is reduced, and that a sheet setting failure occurs and therefore a paper feed failure occurs.
Even in the method of supporting with the elastic support member the tray for stacking sheets, it is possible to maintain the position to which the tray is lowered. However, since, when the tray is separated from the drive portion, the drawing out of a wire is not performed in synchronization with the lowering of the tray, the wire loosens, with the result that, when the wire significantly loosens, the wire may be separated from a pulley.